<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <script src = 'jquery-1.12.4.min.js'></script>
    <title>model</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        .bord{
            border: 1px dashed #ee2602;
            width: 90%;
            margin: 20px auto;
        }
        .title{
            font-size: 20px;
            font-weight: bold;
            margin: 20px;
        }
        .introduce{
            font-size: 16px;
            margin: 0 0 20px 50px;
        }
        .red{
            color: red;
        }
    </style>
    <script>
        jQuery(function($) {

        });
    </script>
</head>
<body>
        <div class="bord">
            <div class="title">标题</div>
            <div class="introduce">介绍内容</div>
        </div>
        <div class="bord">
            <div class="title">演示效果</div>
            <div class="introduce">
                <button>查找所有 name 以 'letter' 结尾的 input 元素，背景变红色。</button>
            </div>
        </div>
        <div class="bord">
            <div class="title">代码</div>
            <div class="introduce">介绍内容</div>
        </div>
</body>
</html>